1. Field of the Disclosure
The present disclosure relates to antenna assemblies for electronic article surveillance (EAS) or radiofrequency identification (RFID) which are made of thin films and/or thin film materials.
2. Background of Related Art
Electronic article surveillance (EAS) systems project a electromagnetic field into an interrogation zone usually at the exit of a retail store. The electromagnetic field excites a marker that returns a signal to the EAS system which alarms to indicate the presence of an EAS marker within the interrogation zone. EAS markers may be placed on merchandise to prevent unauthorized removal of tagged merchandise from a retail establishment, while EAS system transmitter antennas are used to project the electromagnetic field into the interrogation zone. EAS system receiver antennas are used to detect the returned signal from the EAS marker. EAS system transceiver antennas are constructed to perform both transmit and receive functions. By proper design and configuration of the EAS antennas, the system may provide an electromagnetic field of sufficient intensity to adequately excite the EAS marker and provide adequate receive sensitivity so that the return signal received by the EAS system may be detected above the electromagnetic noise in the retail environment.                Properly designed EAS system antennas provide electromagnetic fields that provide the following characteristics:        cover the entire interrogation zone with sufficient intensity field to excite an EAS marker;        have adequate intensity in all spatial orientations throughout the interrogation zone;        do not extend beyond the interrogation zone at high intensities that would cause tagged merchandise outside the interrogation zone to alarm the system; and        comply with regulatory requirements for electromagnetic field emissions.        
In addition, because the interrogation zone is often located in locations where retailers desire to display merchandise for sale, typical EAS antenna systems are either concealed or small and streamlined so that the system installation meets the retailer's aesthetic requirements.
In addition, the system also needs to be designed so that the transmitter(s) and the antenna(s) meet the various regulatory or safety agency requirements.
Traditional EAS systems have relied on antennas that are placed in pedestals positioned on opposite sides of an entrance. The antennas project the magnetic field across the opening. However, there is a practical limit as to how wide of an opening may be covered by an EAS system due to limitations in the size of the antennas and the regulatory or safety limitations on the intensity of the electromagnetic field strength.
As a result, the use of pedestals is often impractical to provide an interrogation zone to cover very large openings such as those at mall entrances or exits due to the challenges in meeting the above listed requirements.
In order to adequately cover a wide area such as a mall entrance or exit, an array of several wire loop antennas may be buried in the concrete under the flooring. Such loop antennas are designed as transceivers and project magnetic fields into the region above the floor to detect the returned signal from the EAS marker. Typically these types of antennas are capable of covering an interrogation zone extending up to about 1.2 meters above the floor. Such an antenna also has the advantage of being modular so that it may be extended to cover various width openings. One such system is marketed by Sensormatic Electronics (Boca Raton, Fla., USA) under the brand name “Floormax”.
Typically, this type of design has the following installation characteristics:                The antenna coils are mounted in the floor and require significant excavation of the sub-floor for installation;        After installation the antennas are encased in concrete that is re-poured over and around the antennas making them inaccessible without further excavation.        
In installations where no metal is present the antennas may be mounted over the sub-floor without excavation. But, due to the thickness of the antenna coil, when antennas are mounted above the sub-floor, layers of additional concrete must be floated onto the surface of the sub-floor to form a gradual slope to cover the antenna. This gradually sloped region may extend several feet on all sides of the antenna. This concrete work is often expensive and may be impractical in some cases.
U.S. Patent Application Publication No. US 2004/0135690 A1, entitled “WIDE EXIT ELECTRONIC ARTICLE SURVEILLANCE ANTENNA SYSTEM” by Copeland. et. al., published on Jul. 15, 2004, and U.S. Patent Application Publication No. US 2004/0217866 A1, also entitled “WIDE EXIT ELECTRONIC ARTICLE SURVEILLANCE ANTENNA SYSTEM” by Copeland et al., published Nov. 4, 2004, both being incorporated by reference herein in their entirety, describe several different systems to cover wide exits or entrances and use various combinations of the following antenna characteristics:                overhead/ceiling mounted ferrite core transceiver or transmitter antennas;        side/wall mounted ferrite core transceiver or transmitter antennas;        overhead/ceiling mounted wire-loop transceiver or transmitter antennas;        side/wall mounted wire-loop transceiver or transmitter antennas;        perimeter wire-loop transceiver or transmitter antennas that extend around the entire perimeter of the interrogation zone;        side/wall mounted core receiver antennas;        overhead/ceiling mounted core receiver antennas;        floor mounted core receiver antennas designed to be mounted in trenches in the sub-floor;        floor mounted loop receiver antennas also designed to be mounted in small trenches in the sub-floor.        
However, systems using receivers in the floor still require cutting trenches in the sub-floor routing of wire-loop or core receiver antennas. This is often undesirable due to the expense and inconvenience to the retailer.
Other efforts have been disclosed using a perimeter wire-loop transceiver or transmitter antenna with added overhead/ceiling mounted or side/wall mounted core receiver antennas to cover the interrogation zone. This solution has been successfully deployed for openings up to 3 meters high and about 5 meters in width. Again, this system also requires cutting trenches in the floor to install wire-loop antenna which is undesirable.
As a result, many known approaches require excavation or trenching of the subfloor to allow installation.